Date: Sun, 29 Jul 2001 13:31:00 +0000 (GMT) From: Evan Sarmiento <ems@open-root.org> To: marki@paradise.net.nz Cc: freebsd-stable@freebsd.org Subject: Re: What about LFS? Message-ID: <20010729133100.58F783A07A@postfix.sekt7.org> In-Reply-To: <3B63D5B6.5E0DF631@paradise.net.nz> (message from Mark Ibell on Sun, 29 Jul 2001 21:21:58 %2B1200)
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hello, First I would like to clarify what "LFS" is, before going into LFS caveats. In LFS, The whole filesyste m is structured as an append-only log to increase performance. Blocks of data are written to the end of the log, thus requiring no seeking. To further aid LFS, when it needs to open a file, an index file is created, where there is a mapping of inodes to physical data blocks where the inodes are held. Basically, LFS is geared torwards writing. Note, when you delete a file on LFS, it does not get deleted until the cleanup takes place, this is where we run into some problems. Problems: - Cleanup degrates performance by %30->%40 precent - You need lots of disk space to run LFS - Your benchmarks are false, look at http://www.usenix.org/publications/library/proceedings/usenix2000/general/full_papers/seltzer/seltzer_html/index.html It appears that Softupdates beats LFS in most cases, Softupdates is a great balance of speed. - Lastly, in 5.0, there's a background fsck, which means that if your computer turns off abruptly, you don't have to wait for fsck to complete, it completes in the background. Thanks Evan Sarmiento >Delivered-To: kaworu@sektor7.ath.cx >Delivered-To: freebsd-stable@freebsd.org >Date: Sun, 29 Jul 2001 21:21:58 +1200 >From: Mark Ibell <marki@paradise.net.nz> >X-Mailer: Mozilla 4.75 [en] (X11; U; OpenBSD 2.9 i386) >X-Accept-Language: en >MIME-Version: 1.0 >Content-Type: text/plain; charset=us-ascii >Content-Transfer-Encoding: 7bit >Sender: owner-freebsd-stable@FreeBSD.ORG >List-ID: <freebsd-stable.FreeBSD.ORG> >List-Archive: <http://docs.freebsd.org/mail/>; (Web Archive) >List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions) >List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-stable> >List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-stable> >X-Loop: FreeBSD.ORG >Precedence: bulk > >Hi, > >With all the debate that has gone on lately about FFS vs EXT2 >performance, stability, etc, I decided to try out NetBSD 1.5.1's LFS. It >looks incredibly promising from the few initial tests I've run on it. As >an example, unpacking FreeBSD 4.3's ports tarball on it takes an >incredible 38s on my Celeron 400 w/ 4GB IDE drive. This contrasts with >about 1m09s for both ReiserFS & EXT2FS and about 6m33s for FFS + >SOFTUPDATES. > >Not only was the speed incredible but you could just whack reset and the >system would mount the LFS filesystem immediately (sometimes with a >brief ~3s checkpoint) and continue booting as if nothing had happened. >Awesome! > >Anyway, I'm curious as to why this code was removed from the FreeBSD >sources some time ago as it appears to show more that a little promise? >Perhaps some reintegration is called for. > >Cheers, >Mark > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-stable" in the body of the message > -- ----------------------------------- Evan Sarmiento | www.open-root.org ems@sekt7.org | www.sekt7.org/~ems/ ----------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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